Field
Embodiments of the present invention generally relate to the field of telecommunications. In particular, various embodiments relate to intelligently routing incoming telephone calls to internal extensions by telephone systems.
Description of the Related Art
Today, telephone system deployments are very important to companies. A telephone system with thousands of extensions may be deployed in a company that has a large services or sales department. These extensions are not typically confined to a specific geographic location and can be spread across regions and boundaries. FIG. 1 conceptually illustrates a block diagram of a typical prior art telephone system 130 with multiple internal extensions. Telephone system 130 comprises a switch 131 and multiple internal extensions 132a-d. Telephone system 130 connects to a network 120, which is an Internet Protocol (IP)-based network or a public switched telephone network (PSTN). Switch 131 is assigned one or more PSTN telephone numbers so that it can be accessed through network 120. The PSTN telephone numbers may be ten digits based on the North American Numbering Plan. Each extension inside telephone system 130 is assigned with an internal extension number by telephone system 130. Internal extension numbers may be 3-5 digits long.
When an incoming telephone call is initiated from an external phone 110 to telephone system 130, external phone 110 dials the PSTN telephone number of telephone system 130. After external phone 110 is connected to switch 131 of telephone system 130, switch 131 may play an option message and ask external phone 110 to dial an internal extension number or transfer the call to an operator. If external phone 110 further dials the internal extension number, then the telephone call is routed to the internal extension with the internal extension number, such as internal extension 132b. When internal extension 132b receives the telephone call from external phone 110, a PSTN number of external phone 110 may be displayed at internal extension 132b. When an outgoing telephone call is initiated from an internal extension (internal extension 132b, for example) inside telephone system 130 to external phone 110, internal extension 132b dials the PSTN number of external phone 110. Switch 131 then tries to establish a connection between internal extension 132b and external phone 110 through network 120. When external phone 110 receives the telephone call from the internal extension 132b, the PSTN number of switch 131 may be displayed at external phone 110 and external phone 110 does not know the internal extension number of the internal extension 132b. 
In some cases, a caller makes a telephone call from an internal extension of the telephone system to a callee who is outside the telephone system but the callee does not answer the telephone call. When the callee wants to later return the caller's call, the callee cannot reach the caller directly because the caller only has the PTSN number of the telephone system without the internal extension number of the caller. Even when the caller leaves a voice message with his internal extension number, it is not very convenient for the callee to return the call as the callee still needs to retrieve the internal extension number from voice mail and dial both the PTSN number of the telephone system and the internal extension number.
In some other cases, when a caller makes a telephone call from an external phone to the telephone system, the telephone call is answered by a random internal extension of the telephone system. For example, a switch or an operator of the telephone system may randomly pick up an available internal extension to answer the incoming telephone call. When the caller calls again, potentially a short time later, it may be that he/she would like the same internal extension to answer his/her call. However, the caller cannot dial the internal extension number because he/she does not know the internal extension number that previously answered. Even when the caller knows the internal extension number, it is still not very convenient for caller repeat the previous call as he/she needs to remember and dial the internal extension number every time he/she makes the same call.
Therefore, there is a need for a more intelligent call management system to select an internal external extension to answer incoming telephone calls.